code: def test_copy_wait_cuda_cpu(cuda_sleep):
      prev_stream = current_stream(torch.device("cuda"))
      next_stream = CPUStream
      _test_copy_wait(prev_stream, next_stream, cuda_sleep)
  
file_path: fairscale/tests/nn/pipe/test_copy.py
imports: import pytest
  import torch
  from fairscale.nn.pipe.copy import Copy, Wait
  from fairscale.nn.pipe.stream import CPUStream, current_stream, get_device, is_cuda, new_stream, use_stream
label_desc: Use image node_id 4 for calling a global function with example usage: test_copy_wait_cuda_cpu(cuda_sleep) without return types